This invention relates in general to circuit breakers and particularly to switched neutral circuit breakers and to circuit breakers that include a ground fault interrupting capability.
Ground fault interrupter (GFI) type circuit breakers and switched neutral (SWN) circuit breakers have been developed in response to a growing need for protection from potentially lethal leakage currents that may develop due to faulty electrical equipment or defective neutral connections. The operation of such circuit breaker is well known in the art. The GFI breakers generally includes a means for sensing an unbalance in the electrical phase and neutral currents flowing to a load circuit, which indicates that some of the current is flowing in paths external to the wired path. Such current is referred to as ground fault current. A particular type of ground fault interrupting circuit breaker manufactured by Square D Company includes a conductive resilient jaw (or stab) for electrically and mechanically engaging one electrical phase busbar and an insulating resilient clamp that clips onto the other electrical phase bus bar for locating and supporting the circuit breaker. Separate phase and neutral connector terminals are provided on the breaker for connection to the appropriate phase and neutral load conductors. The phase conductive path includes a breaker mechanism for interrupting current. A separate stranded wire (pigtail) is provided for connecting the circuit breaker neutral to the panel board or loadcenter neutral. The pigtail is connected to a wire that passes through the window of a ground fault transformer to the neutral connector. A wire in the phase conductive path also passes through the transformer window and couples to the interrupting mechanism of the breaker. The electronics (components and circuitry) for operating the ground fault interrupter are included on a printed circuit board that is mounted in the breaker housing and on which the transformer is secured. Other prior art GFI breakers use "dummy" housings to attach the GFI electronics.
Switched neutral type breakers are used in special environments and generally consist of two-pole housings with only one phase stab being electrically connected to the source. The second phase interrupting mechanism is connected in the neutral load circuit. The neutral is again connected to the panel neutral by means of a stranded wire pigtail.
The above-identified prior art circuit breakers work well, but require extra care and attention during installation and clutter the wireways in the loadcenter because of the need to accommodate the coiled pigtail. Use of more than one of such breakers compounds the cluttered wireway problem. Such breakers also require added manufacturing operations which add to their cost and complexity.
The present invention circuit breaker solves many of the shortcomings of the prior art as exemplified by the above-identified ground fault interrupting circuit breaker.